1. Field of the Invention
The invention relates generally to data processing systems and more specifically to the integration of a commercial instruction processor, a scientific instruction processor and a central processor unit into a single integrated semiconductor chip.
2. Description of the Prior Art
Early data processing systems were designed as a business computer for processing COBOL instructions or as a scientific computer for processing Fortran instructions because the data processing systems were sold into different markets. As data processing system use expanded, business computers were expanded to include a scientific option and scientific computers were expanded to include a business option. The Honeywell H800 data processing system was designed as a business computer. Later systems included a scientific option. Similarly, the General Electric 600 was designed as a scientific computer. Later systems included a business option.
As the semiconductor community developed more sophisticated integrated circuits and as the use of data processing systems expanded, both the scientific and business capabilities were designed into the system.
Data processing systems evolved wherein the logic included a scientific instruction processor (SIP) and a commercial instruction processor (CIP). A central processor unit (CPU) in conjunction with the software operating system delegated scientific instructions to the SIP for execution and business instructions to the CIP for execution. Scientific instructions usually operated on floating point operands which included a mantissa and an exponent. Commercial instructions usually operated on binary coded decimal operands or binary operands in hexadecimal form.
Typical examples which show the operation of the SIP in a data processing system are U.S. Pat. No. 4,295,202 entitled "Hexadecimal Digit Shifter Output Control by a Programmable Read Only Memory", U.S. Pat. No. 4,295,203 entitled "Automatic Rounding Off of Floating Point Operands" and U.S. Pat. No. 4,308,589 entitled "Apparatus for Performing the Scientific Add Instruction".
U.S. Pat. No. 4,390,961 entitled "Data Processor Performing a Decimal Multiply Operation Using a Read Only Memory" and U.S. Pat. No. 4,272,828 entitled "Arithmetic Logic Apparatus for a Data Processing System" show typical examples of the operation of a CIP in a data processing system.
In addition, U.S. Pat. No. 4,258,420 entitled "Control File Apparatus for a Data Processing System" describes the use of a control file in the CIP for storing information received from the CPU. U.S. Pat. No. 4,272,828 entitled "Arithmetic Logic Apparatus for a Data Processing System describes the arithmetic logic apparatus in the CIP having two independent register files, one for each operand. This enhances the execution of arithmetic instructions.
U.S. Pat. No. 4,079,451 entitled "Word, Byte and Bit Indexed Addressing in a Data Processing System", U.S. Pat. No. 4,451,883 entitled "Bus Sourcing and Shifter Control of a Central Processing Unit" and U.S. Pat. No. 4,491,908 entitled "Microprogrammed Control of Extended Integer and Commercial Instruction Processor Instructions through Use of a Data Type Field in a Central Processor Unit" describe typical CPU operations.
The above-issued U.S. patents are assigned to Honeywell Information Systems Inc. and are herein incorporated by reference into this application.
Data processing systems described above have the disadvantage of having some duplication of function. This requires additional logic in the separate processors to perform these functions. In order to be competitive in today's marketplace, systems must be smaller and less costly than was previously acceptable.